Speed suddenly cut in half

Speed test like ml labs and mytest show my speed half of what ookla or cox speed test show. 50m vs the 90m I used to get. This just started happening a few days ago. Cox says everything looks good on their end. Had a few uncorrected errors but only like 20 today. Replaced all cabling and replaced modem. Some webpages load slow. Ml labs sometimes show me as low as 5m. Any help?